The latest online trend has people literally soaking their heads for a good cause. CBS 2’s Lou Young learned more Wednesday about the “ice bucket challenge.”

Call it a “chilly selfie.” In each video a person faces the camera and douses themselves with a bucket of ice water: all kinds of people. Then they contact several Internet “friends” and ask them to accept “the challenge.”

Social media experts say people are finding it difficult to resist.

“There’s a lot of social pressure here. You don’t want to be the guy that didn’t do it,” said Chris Dessi, the CEO of Silverback Social, the world’s leading social media agency.

Anthony Senerchia’s family said they were astounded at how successful it’s been. The Pelham father and husband is suffering from ALS, or Lou Gehrig’s disease, which degenerates muscle tissue. His wife and his niece began an ice bucket challenge in his honor to raise awareness of the disease.

“When we first did this we didn’t want money; we just wanted people to throw buckets of water on their heads to generate awareness,” Jeanette Senerchia said.

But now money is coming in for ALS research, as challengers ask for donations.

“If you dump the bucket on your head you donate an amount of money that is lower than if you don’t dump the bucket. You’re penalized for not being fun, and not being part of the game,” Dessi said.

Anthony Senerchia. A former football player at Pelham High School who coached football until ALS forced him to step away, even accepted the challenge himself, with help from his wife and daughter.

Money started coming in so quickly the family didn’t even have time to set up a website — $2,500 appeared unrequested. They said they don’t know how much they’ll be able to hand over to the researchers at Columbia Presbyterian before it’s over.

Like a traditional chain letter, of course, you can ignore it, act on it or not. But if you act on it, it’s good to wait for a hot day like Wednesday. And as Young found out when he took the challenge, it’s quite refreshing.